Gargasoulas, 26, allegedly drove his car into crowds of pedestrians in the Melbourne shopping district on January 20. He was captured and initially charged with five counts of murder, after a three-month-old baby, a 10-year-old child, and three adults died in the incident. A sixth woman died in hospital 10 days later, and Gargasoulas has now been charged with murder over that additional death.

Victoria Police announced on Friday that he now faces six murder charges, as well as 28 counts of attempted murder and conduct endangering life. Police will allege he deliberately drove his car into the crowds.

"He has also been charged with attempted murder, intentionally cause serious injury, robbery and unlawful imprisonment following two incidents in Windsor prior to the Bourke Street incident," police said in a statement.

"The Homicide Squad are focused on progressing the investigation as a priority and are consulting with Director of Public Prosecution and the State Coroner as the investigation progresses."

Gargasoulas remains in custody, and has been remanded to appear in court again on December 15. He was due in court on March 20, but a scheduled appearance went ahead in his absence.